Willow's brother
by Zarbi
Summary: Harry Potter is the adopted brother of Willow Rosenberg. His only education is magic lessons from her older sister, her wife Tara and Alex's Anya. But for Willow ...
1. Chapter 1 - What the owls deliver letter

**Willow's Brother**

* * *

 **Disclaim** : _This is a cross-over between Harry Potter and Buffy Vampire Slayer. None of these two works belong to me. They are to their respective owners. I don't have the right to these works. All this history is for pleasure._

 **Note** : _The story begins just after the end of the season 7 of 'Buffy against the Vampires'. I don't take into account the seasons 8, 9 and 10 in Comics. And 'Harry Potter', it starts between the 4th and the 5th novel. But the whole Harry Potter story is completely different. We are in an Alternate Universe for Harry Potter and also for Buffy?_

* * *

 **Summary** : _Harry Potter is the adopted brother of Willow Rosenberg. His only education is magic lessons from her older sister, her wife Tara and Alex's Anya._

* * *

 **Chapter One : What the owls deliver letters now?**

In his room near the open window, a black owl suddenly arrives. An owl during the day is an anomaly. But Harry knows the unusual. It is rather usual he doesn't know. But an owl in broad daylight enters quietly in the room and carrying a letter attached to one of its legs is beyond unusual. The owl is laying right next to him and holds the leg where hangs the letter: An owl as a pigeon, what a funny idea.

He takes the paper. It's a letter. He reads on the envelope:

 _ **Harry Potter - Rosenberg**_

 _ **Hotel Hyperion**_

 _ **1481 Hyperion Avenue**_

 _ **Los Angeles**_

 _ **California**_

 _ **USA**_

Harry opens the envelope and pulls out the letter. He reads :

HOGWARTS SCHOOL of WITCHCRAFT and WIZARDRY

Headmaster: Albus Dumbledore

(Order of Merlin, First Class, Grand Sorc., Chf. Warlock, Supreme Mugwump, International Confed. of Wizards)

 _Dear Mr. Potter – Rosenberg],_

 _We are pleased to inform you that you have been accepted at Hogwarts School of Witchcraft and Wizardry. Please find enclosed a list of all necessary books and equipment._

 _Term begins on 1 September. We await your owl by no later than 31 July._

 _Yours sincerely,_

 ** _Minerva McGonagall_**

 ** _Deputy Headmistress_**

Second page

HOGWARTS SCHOOL of WITCHCRAFT and WIZARDRY

* * *

After this letter on another piece of paper, is, a list of materials and books. Most of the material, it has already or he knows how to get them.

The books, he has no idea where he can have them. For the wand, he doesn't understand the reason for which is needed one. It's an inconvenient tool unless you want to do a work of precision with the magic. But as Mr. Albus, his mentor was concerned about it, almost everyone has one but does not much except Anya. Of course, for Willow, he remembers laughing her essays of a wand and the head of Mr. Albus to the fate of those poor wands. They will take seriously them, the day where Willow will be one that works. On the other hand,... Their thoughts stray.

Just then, a gray owl enters his room with a letter attached to its leg. He takes it and reads the same invitation to a magic school in Salem (Massachusetts) with the same list of materials and a list of different books.

Then, Harry takes the 2 letters and brings them to his elder sister Willow and he does not know at all how she will react. She's sometimes very quick-tempered, and she would especially want to know why he had not received an invitation earlier and also why she had never received anything since her power is far greater than his. But he's soon going to be 15 years old. It's more powerful that she in her age but she was unaware of the magic at this age. And therefore a comparison between them is virtually impossible. But it will prevent addiction to the magic that has hit his sister. For this, he must learn magic slowly to absorb it and they may have to invent a way to confront his dark side as the Jedi Knights of Star Wars. Perhaps that these schools of sorcery have a resolution of this problem.

It would be necessary to speak about it in Mr. Albus, he knows it much about magic. Willow would not be also gifted and strong without him.


	2. Chapter 2 - Harry goes to the States

**Chapter 2 - Harry goes to the States**

* * *

 **GB, Surrey, Home Dursley, 13 years ago,**

"You know the whole story. Harry's guard must ensure by a parent of his mother Lilly. Don't ask me why, it's linked to an old rite of the paternal family, Potter. So I Petunia, Lily's sister, I have to assume care from Harry. I did it without hesitation. But the big problem is that the death of my sister and her husband is related to a secret war that plagues from time to time some families of the English nobility. They never speak about it. Alone those who are close to it know. I know it only when the executor has placed Harry at home that I learned it."

Mr. Dursley continues: "The leader of rival faction was killed by Potter. More exactly, they killed each other. But Voldemort, a name of borrowing unquestionably, had co-conspirators who could come to take revenge by killing Harry Potter and his guardians, us. They assure us that it is very unlikely. But Petunia and me, us are anxious for our small Dudley."

"And, the testament says that Harry's custody and the pension which goes with, said Petunia, must go to her closest maternal parents. That is me and you Sheila, my hidden half-sister. I must say that it seems that the paternal branch, Potter, doesn't exist any more or then to distant degrees. In view of the threats which influence Harry, we will prefer that it's you who assure his guard. As you are American and even Californian, you will be in more than 10000 km from England and possible avengers. When will return adult in 16 years, to assure his inheritance, things will have calmed down for a long time."

"So in summary", says Mr. Dursley," do you want to become the guardians of Harry Potter and take him with you live in California? I want to clarify that the pension is a large amount to make him the best possible education."

"I understand your concerns, but is that the executors will accept this change of guardian?"

" No problem, it requires a blood relationship, and you are our although unofficially half-sister, the fact is nothing. For executors, we have the letter of our father talking about his adventure before marriage with our mother and the birth of a baby girl Sheila learned that a few years after his marriage to my mother. As you had an official father who recognized you, it was no use. But to guard Harry, it works. They agree that Harry spent his childhood in the States. This will be more about him."

"Given the situation, if my husband agrees, we are ready to ensure Harry's guard. This will make the greater good for our daughter Willow to have a little brother. Being an only child is not very good according to our studies on child psychology. But we have to see these famous executors to speak with them. Either way, you will agree that we can take him to the United States because I think he needs a passport. It will also require a court judgment on guardianship or family matters. Otherwise, they would be arrested at the airport for child abduction."

" We expected that. But as they are difficult to contact - very old families. I would like to know your availability and what venue you prefer: Here, your hotel or another place. It"s unlikely they invite you home. Oh ! While I think they may ask you a sample of your blood, they can be very prune. As they knew me, they ask me anything. But stories that Lily told me, tell me that it's possible. Blood is very important to them."

* * *

 **Some days later, a Grand hotel in London, GB,**

Rosenberg and the Dursleys meet Albus Dumbledore, the executor of Potter in the restaurant of the Grand hotel.

Sheila thinks:

" _Willow would have called Gandalf. It would be really wonderful in this role."_

The meeting goes well. But as his half sister Petunia had said, Albus requires a specimen of her blood.

A few days later, the Rosenberg returned with their new Member of their family: Harry, a little brother for Willow. Harry has a passport brand new. The Rosenbergs are the new guardians.

What nobody had anticipated is that some months later, the Rosenbergs will move to Sunnydale. They had all 2 a teaching position at the University of Sunnydale. Ms. Rosenberg will soon become a world specialist in child psychology. With her husband, they will embark on extensive tours of conferences first in California, then in the USA and then around the world accompanied by the publication of many books. The result is that much of the education of Harry was made by her sister Willow, assisted by her friends Alex Harris and Jesse McNally.


	3. Chapter 3 - Albus Dumbledore

**Chapter 3 – Albus Dumbledore**

* * *

 _I need a Beta reader or if someone wants to translate from French into English._

* * *

 **HOGWARTS SCHOOL of WITCHCRAFT and WIZARDRY - Scotland - United Kingdom**

Albus Dumbledore, director of Hogwarts school of magic among other distinctions is furious:

"Minerva, I told you: As soon as Harry reappears somewhere you notify me immediately. Instead, you send a standard letter of registration. At the age of 15, he doesn't wait and I remind you that his sister that is probably him educated in magic, is one of the most powerful witches of our time. Is there an answer?"

"You had told me about it years ago. And I forget. So when Harry Potter reappears on our card, I sent him this letter. I receive a response from your famous witch Willow Rosenberg. I'll give you to read."

* * *

 _Headmaster Dumbledore,_

 _Madam Deputy Director McGonagall,_

 _My brother Harry received your owl, the letter of invitation to your school of magic. I will like to know how you get to draw owls to serve pigeon. It's pretty impressive._

 _For your invitation, not knowing your school of Magic and with the agreement of my brother Harry, I refuse. Like since several years, I and my friends will be my brother's magic teachers. He will also go to a normal school where they teach non-magical material according to the laws on the compulsory education of children. All this is done so he can get into a good university. On the other hand, I'll like to have information on university teaching magic._

 _If you do not agree with it, you just tell me about it face to face. You know my address._

 _I want to say that I made the same answer to the Salem school that made the same invitation._

 ** _Willow Rosenberg_**

* * *

"Well, then that's what 'I'll do, Miss Rosenberg, we will meet face to face", Dumbledore said, putting the letter on the desk.

"Minerva, you'll write a letter of protest to Salem to mount our displeasure on having to try to have Harry Potter for them." Then he continues:

"I entrust the reins of the Hogwart's school during my stay in Los Angeles. I'll come back with Harry Potter. Continue to seek a professor of Defense against the Dark Arts. If you find a suitable candidate, let me send his file. It's highly possible that the Ministry imposes a sort of controller on some pretext. The rumors talk about Dolores Umbrage for it. If this is true, you tell me on the spot and you block her to the maximum."

He ends by saying:

"Well, I take care of my trip to Los Angeles and met this Miss Willow Rosenberg. About, you know one thing Miss Rosenberg, Minerva."

"No", she responds.

"This is one of the most powerful witches of our time. You know what happened to Sunnydale to California. She is not for nothing there."

"All I know is that it has destroyed most existing Hell's mouth."

"You are right and I think that Lord Voldemort will be her opponent quite acceptable."

"I remind you prophecy, only Harry can defeat He-Who-Must-Not-Be-Named one of which we can not pronounce the name."

"Yes, but nothing prevents to the fact that it may well be prepared to defeat. And this Willow could do for her little brother Harry finishes the work."

"How do you know so much about this Miss Rosenberg?"

"I watch for some time."

"You knew how long where was Harry?" cries she.

"I tell you on my return", and he is going to his apartment behind his desk.

And on this, Dumbledore returned to his apartments, he must prepare a travel for Los Angeles and he wants to leave this night. And to avoid questions from the magical authorities of the US and the UK and often the questions from Minerva Mac Gonagall, he will take Muggle means and the plane from Glasgow to Los Angeles. By the time they notice it, it may already be back at Hogwarts. He's getting used to this travel.

Minerva returned to his office with a lot of questions in his mind about Harry, this Willow and what did Dumbledore with these 2 there. Because normally, Harry should start his 5th year at Hogwarts in September and think only of his O.W.L.


	4. Chapter 4 - Dumbledore in Los Angeles

**Chapter 4 - Dumbledore in Los Angeles**

* * *

 _I need a Beta reader or if someone wants to translate from French into English._

* * *

 **Los Angeles Airport, USA,  
**

Dumbledore is struggling to recover from the trip. More than 11 hours of travel sitting in the bad seats in the second class. He should take the ultra comfortable seats of business class. But in return, he may have to do it and he will do it with his own funds. He's rich, but good must not abuse it. And it is hard to see how to get to the account of Hogwarts.

In this gigantic airport, how to find your way? The signs aren't made for dogs. He can use magical means such as powder floo or worse the transplanage to join the Hyperion hotel. But he knows the type of people that is there: survivors of the Hellmouth who shoots first and speaks after like the old mentality of the West American. He spotted where the taxis are. It gives the driver the address that exclaims.

\- Well, nobody was going to this hotel for years and now I do several races daily by the hotel. Are you all alone?

Dumbledore told him aback,

\- Yes of course. Why are you asking me this question?

\- Most travelers were young girls alone or accompanied. I believe that you are the first lonely old man that I take there.

Dumbledore's eyes widen. He doesn't understand. The driver sees that look in the mirror and says:

\- Don't ask me questions, I don't know the reason for all this. I asked the question and didn't answer or that it wasn't my business.

And on that, the taxi leaves in direction of the Hyperion hotel. So accustomed to this new address, the taxi driver does even not use his GPS to go.

* * *

 **Hotel neighborhood Hyperion, Los Angeles, California, USA,**

After almost an hour, the taxi drops Dumbledore off at a hundred meters from the hotel on request. He wants to observe this hotel before going there. Following the practice, he gives a good tip with the fare at the taxi driver. This isn't the Magic Bus or its US equivalent.

First, he examines the hotel with his own eyes while circling the block quiet steps. Then he casts some observation spells to see the magical defenses of the Hotel. Because he saw the many comings and goings in the hotel and if Harry lives there, he doesn't enjoy the wards of a family home. The sacrifice of his mother tied to a blood spell allows him to be protected against good numbers of bad spells if he lives in the home of the maternal family member.

He finds that there is nice and good defenses magic but they are particularly against the Creatures of the night. And there are others that he has never met, and for some, it's just the footnotes page in some forgotten books. It would have been unable to establish itself. He recalls just have felt in very old magic buildings. But for a true Wizard, is a mess. The main defense is especially the residents of the hotel and its visitors as it has observed and they are not mere Muggle, but other things. It remains to be who they really are.

But this is the time of the confrontation and after this review, it verifies that 'there are many letters in the inside pocket and walks briskly to the door of the hotel Hyperion. It's day and a beautiful California sun so there will be no problem in with the creatures of the night.

Arrived at 3 m before the door, he' hearing a familiar voice behind him.

\- Hello Mr. Albus, So what do we owe to the pleasure of your company today?

He turns and he says,

\- Hello, ….

* * *

 _I'll let you Guess what the person who comes say hello?_


	5. Chapter 5 - What the Rosenbergs

**Chapter 5 - What the Rosenbergs in Sunnydale?**

* * *

 **Fifteen Years before the Fall of Sunnydale \- **

**Hogwarts - End of year**

As well often, this year, the Slytherins again won the cup of the 4 houses and their arms weapons have flared up the walls of the great Hall of Hogwarts. Right now, all students have taken the Hogwarts Express to London and return to their families for the summer holidays.

Now, Albus Dumbledore has time to deal with different tasks he has put on hold with the end of the school year. And inside, he finds a letter from the United States coming to the Rosenbergs. It's rather heavy and contains pictures of Harry Potter.

This is indeed the case. Of course, these are Harry pictures where the subjects do not move. But he sees that Harry was in good shape and everything looks fine. There is even a picture of him on a small bicycle with training wheels on the back. He sees for the first time, their eldest daughter Willow, a redhead.

Then he reads their letter and this is the real horror. The Rosenberg moved to Sunnydale, California. It is the most active Hellmouth on Earth. It attracts all the demons and vampires. If this is the case, he should have left Harry with the Dursleys, there would be more to the shelter there.

Then he said he was misunderstood. He rereads the letter very carefully. The Rosenbergs have a position of full professor at the University of Sunnydale. And as they say in their letter, 5 to 10 years there and it's the most prestigious American universities, which they open big arms.

Albus doesn't like it, he feels that they have been attracted there. They'll have to exit thi town. He'll have to go to Sunnydale, one of the most dangerous places in the world. This will remind him the war against Grindenwald when he was young at the time and he holds strong against him his elder wand.

Going to go to Sunnydale. This isn't the holiday he had hoped.

 **San Francisco, California, USA, Month of June**

It's not possible. They have already moved to Sunnydale. They hung for a good part of the summer to get them another job elsewhere. Supposedly, they had a superb real estate opportunity. And they must ensure a seminar this summer at Sunnydale University. For him, all that smells the set-up written all over. But who and why? are the questions to which he has no answer now.

Good, going to contact his friends to the American Ministry of magic to find a better position for the Rosenbergs, or even England if necessary. He thinks that they will not refuse a position at Cambridge or Oxford. This would be a good idea get those out in England. It will have fewer unpleasant surprises.

Good Tomorrow, he will go to Sunnydale to see the new Rosenberg's house. He will take this opportunity to install all the defenses necessary for their protection in this cursed city and especially avoid Harry to take a black tint to its magic.

 **Los Angeles, California, USA,**

The Rosenberg's house is protected as best it could in one day. He discreetly put the anti-vampire revulsive and also against others creatures of the night. It's far from enough, but they will have to do for now. But he has no intention of letting living them there long. He managed to make them believe that they had won a week's stay at Disneyland from next Saturday.

Upon their return, they will have a nice surprise and for that, he must go to Washington to the American Ministry of magic. This will cost him many favors. But the Rosenbergs will not stay at Sunnydale with Harry. Especially as the Sunnydale complex begin to affect them.

And so,

Appears a door in his hotel room and knock on it.

Albus Dumbledore has the habit of magic, but that he doesn't know this kind of magic and has never heard except in a few tales.

He hears a voice:

'May I come in, Mr. Dumbledore?' I would not want you to throw me a bad spell.

"You can open the door", says Dumbledore figuring that this is not really an invitation to enter.

The door opens and enters a white man with brown hair and black eyes and medium size. He says:

"I introduce myself Whistler. I'm a demon of the Balance and the ambassador of the Powers To Be. There are some legends about us in the wizarding world.

"Right", think Dumbledore.

"I'm sent by them to you because of something strictly unforeseen and which could never take place, happened. The Rosenberg gathered Harry Potter, the hero of the Wizard world of the United Kingdom and who must fight against Lord Voldemort. But unexpectedly, it was gathered by the Rosenbergs, whose their daughter Willow you met is called to become the most powerful witch of our time."

"Impossible, I did some basic tests and she is only a very ordinary Muggle although very intelligent."

"The usual magic tests don't react. But her magic is very special and powerful and must develop in a very special environment: Sunnydale. In the end, she will have the power of Merlin. Willow will not move from Sunnydale except for a few short vacations. And as Harry is her adopted brother, he won't move too. That is the decision by the Powers and your power can nothing against. "

Dumbledore is red with anger.

"Before you scream, the Powers agree to give vitals information to you. We want to inform you that as you thought, Lord Voldemort alias Tom Riddle survived the mortal fate, but in a half-ghostly form. He was able to survive thanks to Horcruxes", says Whistler.

Albus Dumbledore looks pale.

"I see you know what it is. He has made it 7. The Powers have authorized me to show you where you can find 2 of these Horcruxes. The first is in your school at Hogwarts in the Demand Room in the form of the Great Storeroom. The Horcrux is in the diadem of Ravenclaw."

"The second is the Gaunt ring which is hidden in the Gaunt's House, the descendants of the Slytherin and Peverell families. It's in Little Hangleton aloof in the small wood. Be careful, this ring is protected by powerful blacks spells. Moreover, the black stone of this ring is one of the 3 relics of Death: the Resurrection Stone. You will have the 3 Relics of Death. They have not been getting together for generations."

Albus blushed.

" Three other Horcruxes are inaccessible at the moment. Another, we don't quite know where it is for now and the last must play a big role soon. "

"Thank you for this information, but Harry Potter is in danger in a city as dangerous as Sunnydale."

"Sunnydale is the most dangerous city in the world. But we agree that Harry will be protected the same way as Willow and her parents. We take this opportunity to confirm the prophecy concerning Harry Potter and Lord Voldemort. One must defeat the other to live".

"The Powers are telling me that you have a right of glance at Harry Potter and warns that Willow will need a great teacher of magic when her magic awaken. They thought of you."

And that's interesting for Albus Dumbledore.


	6. Chapter 6 - Adults talk

**Chapter 6 - The adults talk**

* * *

"Hello, Mrs. Rosenberg, I'm glad to see you survived the catastrophe of Sunnydale".

"By chance, we had a seminar at Harvard and a series of conferences in New England with my husband. We interrupted it with the news. Willow and Harry just survived, but they have only saved what they were carrying on them at that time and a little bag. In short, we lost everything except our lives."

"Good, you're all alive and healthy, that's the main thing."

"But how did you know that we were at this hotel?"

"As soon as I learned of the destruction of Sunnydale, I contacted people who were specialized in the research of people and as soon as they had your new temporary address, they gave it to me and I came to see How you go and know what you are going to do after?"

"We're not going to talk about it on the sidewalk, I invite you to the hotel, to discuss it and you can see your protégé, Harry," says Mrs. Rosenberg.

"Thank you", says Dumbledore.

And on these words, they enter the hotel and go into a sitting area where by chance they find an unoccupied table. Dumbledore observes those present, especially many girls and young women. Their appearance, their presence reminds one of them.

Sitting, they talk again.

'So you told me that Harry had survived without injury the Sunnydale's disaster. But would he have a problem with lost papers?

"No, by chance, Willow and Harry had made a little bag of necessity with everything needed to rebuild a new life and they took before fleeing. I think their bus was the last one to leave Sunnydale before its collapse."

"But they have seen before the collapse of the horrible things they said little. I think they see a psychologist who specializes in the survivors of the disaster."

"One of your confreres", says with a smile Dumbledore

"Hey! Yes. I can't deal with them because I'm too involved because I'm their mother. But you will also have to discuss magic with Willow because I believe she has cast a spell that affects the entire planet."

"I doubt it a little."

"Do you see all these young girls?"

"Yes", says Dumbledore

"For the most part, they are Vampire Slayers".

"But there's only one Slayer in the world? And it was Faith Lehane who was. Buffy had kept her powers after her first death."

"She's still. But Willow has made all Potentials in the age of being, Vampire Slayers perfectly active. Finally, all those who said yes. It's exciting for a child psychologist to know how and why they said yes. But pity, I don't think I can make an article on it."

"Who knows one day, he could come out, written by a witness and a specialist in adolescent psychology."

"Yes, I think that one day, all this will be public and there, my article will be published and it will be a reference. Good idea, we'll think about it and my husband Ira. The only problem is that there is no Nobel Prize for psychologists."

"Also what is the equivalent?"

"There's not really any. There is the Grawmeyer Award or the International Psychological Congress Award for a career."

The two people drink a sip of their cup of coffee.

"Otherwise, Willow has changed physically, her red hair has turned white,' continues Ms. Rosenberg.

"This means she has cast a considerable spell and she has gone beyond her strength, it could have killed her."

"She knows, but she believes she was the only option and I agree with her. "

"It should be examined and at least a complete health check with the best specialists. For I think the spell has left other physical traces."

"I suggested her. But when it comes to magic, she listens to you while I ...

"And if not for my godson Harry?'

"All is well," he did good of this disaster. she said.

"No annus horribilis", says Dumbledore, smiling.

"It was true, two years ago, with Gloria, the goddess of hell."

There is 2-3 minutes off when thinking about this and they drink their coffee. Above all, he recalls the difficulty of resurrecting Buffy, something he thought impossible at first.

"Otherwise for Harry, the school look good like the magic. Good student in turn, although he has a passion, a little too for firearms and he's doing well. But I don't want a gun in the house. But at Buffy's home, it became an arsenal, continues Mrs. Rosenberg. For the magic, you see with Willow, she can tells you more. If not for his love, he's dating Dawn Summers, Buffy's younger sister"

The Key expresses Albus Dumbledore, one of the potentially most powerful creatures of the Earth. If she accesses to all her power, she'll completely surpass Willow as she passed him. But he has no idea how do and he thinks in his heart that this isn't desirable for Earth.

"Do you think going to England this summer? That's why I asked you the question for identity papers. An absurd controversy begins, saying that Harry Potter, heir of the fortune and the title of Lord Potter is dead. The simplest to kill this rumor in the bud is by introducing Harry to some influential people. In addition, it's time to enter this environment. I wanted to do for a long time, but given everything that was going on at Sunnydale, I didn't dare.

Mrs. Rosenberg shows ostensibly an air of complete incomprehension.

"I had never said to you, but the Powers that support you wanted Buffy to Sunnydale and did everything to make your stay there. Now that Sunnydale is destroyed, there is no longer scarce on you. You are free to establish you where you want. I want to say that these powers to protect you. You noticed nothing unusual up to Willow, of her own will, is involved in fighting with the Slayer Buffy Summers."

The conversation continues for a long time, completely upsetting Ms. Rosenberg, who wonders how she will explain everything to her husband.


End file.
